Commit ea9b9907 authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds
Browse files

fuse: implement perform_write



Introduce fuse_perform_write.  With fusexmp (a passthrough filesystem), large
(1MB) writes into a backing tmpfs filesystem are sped up by almost 4 times
(256MB/s vs 71MB/s).

[mszeredi@suse.cz]:

 - split into smaller functions
 - testing
 - duplicate generic_file_aio_write(), so that there's no need to add a
   new ->perform_write() a_op.  Comment from hch.
Signed-off-by: default avatarNick Piggin <npiggin@suse.de>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 854512ec
......@@ -677,6 +677,198 @@ static int fuse_write_end(struct file *file, struct address_space *mapping,
return res;
}
static size_t fuse_send_write_pages(struct fuse_req *req, struct file *file,
struct inode *inode, loff_t pos,
size_t count)
{
size_t res;
unsigned offset;
unsigned i;
for (i = 0; i < req->num_pages; i++)
fuse_wait_on_page_writeback(inode, req->pages[i]->index);
res = fuse_send_write(req, file, inode, pos, count, NULL);
offset = req->page_offset;
count = res;
for (i = 0; i < req->num_pages; i++) {
struct page *page = req->pages[i];
if (!req->out.h.error && !offset && count >= PAGE_CACHE_SIZE)
SetPageUptodate(page);
if (count > PAGE_CACHE_SIZE - offset)
count -= PAGE_CACHE_SIZE - offset;
else
count = 0;
offset = 0;
unlock_page(page);
page_cache_release(page);
}
return res;
}
static ssize_t fuse_fill_write_pages(struct fuse_req *req,
struct address_space *mapping,
struct iov_iter *ii, loff_t pos)
{
struct fuse_conn *fc = get_fuse_conn(mapping->host);
unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
size_t count = 0;
int err;
req->page_offset = offset;
do {
size_t tmp;
struct page *page;
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
size_t bytes = min_t(size_t, PAGE_CACHE_SIZE - offset,
iov_iter_count(ii));
bytes = min_t(size_t, bytes, fc->max_write - count);
again:
err = -EFAULT;
if (iov_iter_fault_in_readable(ii, bytes))
break;
err = -ENOMEM;
page = __grab_cache_page(mapping, index);
if (!page)
break;
pagefault_disable();
tmp = iov_iter_copy_from_user_atomic(page, ii, offset, bytes);
pagefault_enable();
flush_dcache_page(page);
if (!tmp) {
unlock_page(page);
page_cache_release(page);
bytes = min(bytes, iov_iter_single_seg_count(ii));
goto again;
}
err = 0;
req->pages[req->num_pages] = page;
req->num_pages++;
iov_iter_advance(ii, tmp);
count += tmp;
pos += tmp;
offset += tmp;
if (offset == PAGE_CACHE_SIZE)
offset = 0;
} while (iov_iter_count(ii) && count < fc->max_write &&
req->num_pages < FUSE_MAX_PAGES_PER_REQ && offset == 0);
return count > 0 ? count : err;
}
static ssize_t fuse_perform_write(struct file *file,
struct address_space *mapping,
struct iov_iter *ii, loff_t pos)
{
struct inode *inode = mapping->host;
struct fuse_conn *fc = get_fuse_conn(inode);
int err = 0;
ssize_t res = 0;
if (is_bad_inode(inode))
return -EIO;
do {
struct fuse_req *req;
ssize_t count;
req = fuse_get_req(fc);
if (IS_ERR(req)) {
err = PTR_ERR(req);
break;
}
count = fuse_fill_write_pages(req, mapping, ii, pos);
if (count <= 0) {
err = count;
} else {
size_t num_written;
num_written = fuse_send_write_pages(req, file, inode,
pos, count);
err = req->out.h.error;
if (!err) {
res += num_written;
pos += num_written;
/* break out of the loop on short write */
if (num_written != count)
err = -EIO;
}
}
fuse_put_request(fc, req);
} while (!err && iov_iter_count(ii));
if (res > 0)
fuse_write_update_size(inode, pos);
fuse_invalidate_attr(inode);
return res > 0 ? res : err;
}
static ssize_t fuse_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
struct file *file = iocb->ki_filp;
struct address_space *mapping = file->f_mapping;
size_t count = 0;
ssize_t written = 0;
struct inode *inode = mapping->host;
ssize_t err;
struct iov_iter i;
WARN_ON(iocb->ki_pos != pos);
err = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
if (err)
return err;
mutex_lock(&inode->i_mutex);
vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
/* We can write back this queue in page reclaim */
current->backing_dev_info = mapping->backing_dev_info;
err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
if (err)
goto out;
if (count == 0)
goto out;
err = remove_suid(file->f_path.dentry);
if (err)
goto out;
file_update_time(file);
iov_iter_init(&i, iov, nr_segs, count, 0);
written = fuse_perform_write(file, mapping, &i, pos);
if (written >= 0)
iocb->ki_pos = pos + written;
out:
current->backing_dev_info = NULL;
mutex_unlock(&inode->i_mutex);
return written ? written : err;
}
static void fuse_release_user_pages(struct fuse_req *req, int write)
{
unsigned i;
......@@ -1203,7 +1395,7 @@ static const struct file_operations fuse_file_operations = {
.read = do_sync_read,
.aio_read = fuse_file_aio_read,
.write = do_sync_write,
.aio_write = generic_file_aio_write,
.aio_write = fuse_file_aio_write,
.mmap = fuse_file_mmap,
.open = fuse_open,
.flush = fuse_flush,
......
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